One of the unique characteristics of the ICBM is its ability to carry a large payload. This capability enables new nuclear weapons states to compensate for relatively inaccurate missiles by means of mounting a warhead with a large nuclear yield atop the missile. However, as technology improves and guidance systems allow for reductions in yield, nations may still opt for the ICBM because it can also carry many light warheads. The missile can carry penetration aids, such as decoys, to help confuse ballistic missile defenses, or a post-boost vehicle to launch several warheads over different trajectories to strike many targets (multiple independently targetable reentry vehicles, or MIRVs). ICBMs that carry more than two RVs are called multiple reentry vehicles.
The U. S. Air Force also developed and deployed the Titan series of ICBMs. Titan development started in 1955. The system was designed as a backup to Atlas and provided the air force with a two-stage, liquid-fueled ICBM that eventually would have a longer range and larger payload than the Atlas. Titan I, which served from 1962 until 1965, had a range of 6,300 miles and could carry a multimegaton nuclear warhead, and its crews needed only 15 minutes to launch their weapon. Titan II had much better performance: With a 9,000-mile range, it could carry a 9-megaton warhead, the largest single warhead ever carried by a U. S. ICBM. Titan II was also more responsive than the Atlas. Crews required only a single minute to launch the missile. Fifty-four Titan IIs defended the nation from 1963 to 1987. Both Titan I and Titan II were silo-based systems.
U. S. Air Force officials, impressed with propellant developments in the 1960s, moved to build a solid-fueled ICBM. Ultimately, the air force would design and deploy three versions of the Minuteman, the first such missile to be built in the United States. Minuteman used a three-stage, solid-fueled rocket motor system and was deployed in underground silos. Minuteman I had a range of 6,300 miles and carried a single reentry vehicle with a 1-megaton yield. This model first went on alert in 1962, and 800 missiles eventually served the country. Minuteman II started to replace the earlier model in 1967. It carried a warhead with a 1.2-megaton yield and had longer range, improved guidance, and penetration aids. Minuteman II served until 1991. A Minuteman III design began in 1964. It had a range of 8,000 miles and carried two to three RVs with a yield of 170 to 375 kilotons. The U. S. Air Force built 500 Minuteman III ICBMs, which continue to serve today.
The Peacekeeper is the latest U. S. ICBM (the single- warhead Midgetman was under development when it was canceled at the end of the Cold War). The Peacekeeper was designed to carry ten RVs, each having a yield of 300 kilotons. Initial air force design efforts concentrated on developing an air- or ground-mobile ICBM to replace the silo-based, and increasingly vulnerable, Minuteman system. Many concepts were tested, and in 1977, air force officials selected a four-stage missile that could be deployed in existing Minuteman silos. The Peacekeeper’s range is more than 6,780 miles. The first three stages are solid-fuel systems, and the fourth stage has a liquid- fueled motor. The Peacekeeper was acquired to replace the Minuteman system, but the treaty resulting from the Strategic Arms Limitations Talks (SALT II) limited the number of ICBMs with multiple RVs. These arms control provisions led to an agreement stipulating that the United States would deploy only fifty Peacekeeper missiles. Peacekeeper is scheduled to be withdrawn from service by 2007.